#include<stdio.h>
#include<stdlib.h>

int main(int argc,char *argv[])
{
	int ch1,ch2;
	FILE *f1;
	FILE *f2;

	if(argc!=3)
	{
		printf("Usage: %s file1 file2\n",argv[0]);
		exit(EXIT_FAILURE);
	}
	if((f1=fopen(argv[1],"r"))==NULL)
	{
		printf("Could not open file %s for input\n",argv[1]);
		exit(EXIT_FAILURE);
	}
	if((f2=fopen(argv[2],"r"))==NULL)
	{
		printf("Could not open file %s for input\n",argv[2]);
		exit(EXIT_FAILURE);
	}
	ch1=getc(f1);
	ch2=getc(f2);

	while(ch1!=EOF||ch2!=EOF)
	{
		while(ch1!=EOF && ch1!='\n'){
			putchar(ch1);
			ch1=getc(f1);}
		if(ch1!=EOF){
			putchar('\n');
			ch1=getc(f1);}
		while(ch2!=EOF&&ch2!='\n'){
			putchar(ch2);
			ch2=getc(f2);}
		if(ch2!=EOF){
			putchar('\n');
			ch2=getc(f2);}
	}
	if(fclose(f1)!=0)
		printf("Could not close file %s\n",argv[1]);
	if(fclose(f2)!=0)
		printf("Could not close file %s\n",argv[2]);

	return 0;
}

